Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1995-05-08
2001-04-10
Hong, Stephen S. (Department: 2776)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000
Reexamination Certificate
active
06216144
ABSTRACT:
The invention relates to a data processing system comprising a visual display unit (VDU) of the raster type with a plurality of rasterpoints and comprising means for generating reduced images for display on the VDU from an original image available as an original set of pixel values, in which reduced images portions of the original image are represented by single pixels. Such a data processing system is for example used in an office environment were files, each consisting of a number of pages, are handled. The number of pages in a file may become pretty large, and reach, for example, several hundreds. In such an environment it is necessary to obtain an impression of the kind of documents and of the file by browsing through file contents without the need to see each individual page in a size that is sufficiently large to read. Only when a particular page, or a set of pages needs to be read or annotated, or the text on it changed, a full size copy of the page or the text is made available to the user of the system.
Such a data processing system is known from WO 89/11695. In the known data processing system pages from files or documents are presented in reduced format on a visual display unit (VDU). From an original image available as a set of original pixel values, for example a page of text scanned by an image digitizer, a reduced image is generated by subdivision of the original image in blocks of pixels and representing each such block by a single pixel in the reduced image. To determine the pixel values for this reduced image the average pixel value in the original block is taken into account supplemented with a contrast enhancement procedure. The pixel value of each pixel in the reduced image is determined not only from the average pixel value in the original block, but also in relation to the pixel values in the adjacent blocks.
A reduction with a linear factor of eight is described in WO 89/11695 as giving acceptable results. However a significant further reduction will be difficult to achieve because by such a further reduction of, for example, a page of text, the necessary block size will become larger and the averaged pixel values will become approximately the same, which will result in a reduced image in which all pixels, or a very large majority of them have the same, or approximately the same, pixel value. No details of the lay-out of such a reduced page are distinguishable any more and the user of the system is unable to recognize pages as being of particular interest or of no interest at the moment for him/her. A smaller reduction is then necessary but that inhibits the possibility to obtain in one glance an impression of a large number of pages of a file or document, and thereby of the kind of file.
It is, inter alia, an object of the invention to provide a data processing system in which the user can get a feeling of the contents of a file or a document by the display of all pages in the file or a large number of them in the form of extremely reduced images.
It is also an object of the invention to provide a method for generating an image in reduced format, in particular of a page of text, whereby the lay-out of the page of text is sufficiently recognizable to identify the type of page from the reduced image.
It is a further object of the invention to provide a method for display of a large number of pages of text from a document or file whereby an impression of the type of document or file can be obtained in one glance to a large number of reduced images.
To obtain the necessarily (extremely) reduced images in a way that allows recognition of the type or lay-out of each page the data processing system according to the invention is characterized in that the means for generating reduced images comprise image reduction means for determining a greylevel or colour to be assigned to pixels in the reduced image as a function of a pattern of pixel values in the portion of the original image to be represented by single pixels in the reduced image, in that each rasterpoint of the VDU is adjustable to one of a plurality of greylevels or colours and in that each pixel in the reduced image in the displayed reduced image is shown by one rasterpoint of the VDU. The reduced images are displayed on a screen that allows various intensities for each pixel. The reduction algorithm determines the greylevels in the reduced image in dependence of the configuration of pixel values in the portions of the original image corresponding to each pixel in the reduced image, not only on the basis of the average pixel value. By use of a suitable way of coding sufficient detail of the lay-out of a page can be retained in the reduction procedure.
Preferably the data processing system according to the invention is further characterised in that the image reduction means comprise first processing means for reducing the original image to an intermediate image and second processing means for reducing an intermediate image to the reduced image wherein the second processing means are arranged for determining greylevels or colours of pixels in the reduced image while incorporating the configuration of pixel values in the portions of the intermediate image to be represented by said pixels in the reduced image. To obtain significant reduction each pixel in the reduced image has to correspond to a relatively large block of pixels in the original image. Even if the pixels of the original image can adopt only one of two values, white—or “on”—and black—or “off”—the number of possible patterns in that block of pixels becomes soon very large and, consequently, the analysis of the pattern becomes cumbersome and time-consuming. By splitting of the reduction procedure in two steps the analysis of the blocks of pixels of the original image to obtain one pixel of the reduced image can be done very rapidly.
To this effect a data processing system according to the invention may be characterised in the second processing means is provided with a look-up table of possible configurations of pixel values for determining the greylevel or colour of a single pixel in the reduced image from the configuration of pixel values in a portion of the intermediate image. When there is only a restricted number of different configurations possible for each block of pixels in the intermediate image the use of a look-up table is a very fast way of translating the configuration into a pixel value of the reduced image while at the same time no excessive memory requirements are necessary.
An embodiment of the data processing system according to the invention is characterised in the second processing means are arranged for representing a block of three by three pixels (1-9) in the intermediate image by one pixel in the reduced image. Such a reduction puts moderate requirements to the available resources for calculating the pixel value or storing a table of configurations. For example, there are only 2
9
=512 black/white configurations for such a block and a corresponding number of entries in a look-up table. Also a four by four block, with 2
16
=65536 possible black and white configurations would not impose an impossible burden on the data processing system in view of the present-day costs for memory capacity.
To obtain the intermediate image from the original image the data processing system according to the invention is characterised in that the first processing means are arranged for generating the pixels in the intermediate image by run-length coding of the pixels of the original image. It has appeared that such a reduction algorithm achieves considerable reduction without losing to much detail in the global lay-out of a page. A reduction with a factor of about twenty is possible.
These and other, more detailed, aspects of the invention will be apparent from and elucidated with reference to the drawings and embodiments described hereinafter.
REFERENCES:
patent: 4153896 (1979-05-01), White
patent: 4445137 (1984-04-01), Panofsky
patent: 4649380 (1987-03-01), Penna
patent: 4885786 (1989-12-01), Anderson et al.
patent: 4970604
Hong Stephen S.
U.S. Philips Corporation
Verdonk Peter
LandOfFree
Data processing system with means for display of reduced... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Data processing system with means for display of reduced..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data processing system with means for display of reduced... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2549268